The download link does not take you to an API description page, but rather calls the API directly. You can call the API directly with the following URL (returns in JSON) format:
http://api.civicapps.org/business-licenses/

I was curious about the GIS prefixed fields. For instance are GISX, and GISY useful for lookup in other public data sources. Such as latitude and longitude being useful in a mapping service such as google maps.

The GISX / GISY and Latitude / Longitude fields provide an X/Y coordinates for the feature provided by the API. GISX / GISY are in the Oregon Stateplane North / NAD83 projection while the Latitude / Longitude is in the standard geographic coordinate system. These fields can be used to locate the feature using a map or GPS system, and can also be used to relate them spatially to other GIS data sources. These locations are based on address and other information from the license system and may vary in spatial accuracy